19 years after 9/11, Americans continue to fear foreign extremists and underplay the dangers of domestic terrorism

On a Tuesday morning in September 2001, the American experience with terrorism was fundamentally altered. Two thousand, nine hundred and ninety-six people were killed as the direct result of attacks in New York, Washington, D.C. and Pennsylvania. Thousands more, including many first responders, later lost their lives to health complications from working at or being near Ground Zero.

Nineteen years later, Americans’ ideas of what terrorism is remain tied to that morning.

The 9/11 attacks were perpetrated by al-Qaida terrorists. They resulted in nearly 18 times more deaths than America’s second most devastating terrorist attack — the Oklahoma City bombing that occurred 15 years earlier. That intense loss of life has meant that the 9/11 attacks have come to symbolize terrorism for many Americans.

But focusing solely on Islamist extremism groups like al-Qaida when investigating, researching and developing counterterrorism policies does not necessarily align with what the numbers tell us. Homegrown far-right extremism also poses a persistent and lethal threat to the lives and well-being of Americans. This risk is often underestimated because of the devastating impact of the 9/11 terrorist attacks.
By the numbers
Historically, the United States has been home to adherents of many types of extremist ideologies. Our 15 years of research shows the two current most prominent threats are motivated by Islamist extremism and far-right extremism.